In depth comparison and review of Realme C21 and OPPO A57s. Compare sizes, cameras, batteries, memory, and other important specifications and features to easily choose the right phone for you. Our goal is to help you uncover differences between the products and find the phone that will best fit your needs.
| DESIGN AND DIMENSIONS | Realme C21 | OPPO A57s |
|---|
| Product Type | Smartphone | Smartphone | |
|---|---|---|---|
| Manufacturer Model Number | - | CPH2385 | |
| Form Factor | Touch | Touch | |
| Height | 165.2 mm | 163.74 mm | Realme C21 has greater height than OPPO A57s. |
| Width | 76.4 mm | 75.03 mm | Realme C21 has greater width than OPPO A57s. |
| Depth | 8.9 mm | 7.99 mm | OPPO A57s is narrower than Realme C21. |
| Weight | 190 g | 187 g | OPPO A57s is lighter than Realme C21. |
| Body Colour | Cross black | Cross blue | Starry black | |
| Body Material | - | Composite polymer | |
| Waterproof (Water-resistant) | - | - | OPPO A57s is waterproof. |
| IP rating | - | IPX4 | |
| SAR Value | - | 1.015 W/kg (body), 0.957 W/kg (head), 2.399 W/kg (limb) | |
| Connector Type | Micro-USB Headset jack - mini-phone 3.5mm |
Headset jack - mini-phone 3.5mm USB Type-C - 24 pin USB-C |
|
| SIM Card Type (Size) | Nano SIM | Nano SIM | |
| SIM Card Qty | Dual-SIM | Dual-SIM | |
| SIM Card Configuration Details | - | Nano SIM + nano SIM/microSD |
| DISPLAY | Realme C21 | OPPO A57s |
|---|
| Display Type | LCD display | LCD display | |
|---|---|---|---|
| Display Technology | LCD | LCD | |
| Screen Size (Display Size) | 6.5" | 6.56" | OPPO A57s has larger screen size than Realme C21. |
| Screen Resolution (Display Resolution) | 1600 x 720 pixels | 1612 x 720 pixels | OPPO A57s has better screen resolution than Realme C21. |
| Display Format | HD+ | HD+ | |
| Pixel Density | - | 269 ppi | |
| Aspect Ratio | 20:9 | 20.1:9 | |
| Max Brightness | 420 cd/m² | 600 cd/m² | OPPO A57s has better display brightness than Realme C21. |
| Colour Depth | - | 16.7 million colours | |
| Contrast Ratio | - | 1500:1 | |
| Display Refresh Rate | - | 60 Hz | |
| Touch Sampling Rate | - | 60 Hz | |
| Display Features | Mini-drop display | Night mode, Eye comfort mode, 96% NTSC | |
| Display Protection (Screen Protector) | - | Panda Glass MN228 |
| PROCESSOR | Realme C21 | OPPO A57s |
|---|
| Processor Type (CPU) | MediaTek Helio G35 | MediaTek Helio G35 | |
|---|---|---|---|
| Clock Speed | 2.3 GHz | 2.3 GHz | Both phones have the same clock speed. |
| Processor Core Qty | 8-core | 8-core | Both phones have the same number of phone cores. |
| Graphics System (GPU) | PowerVR GE8320 | IMG GE8320 |
| MEMORY | Realme C21 | OPPO A57s |
|---|
| RAM | LPDDR4X SDRAM - 3 GB | LPDDR4X SDRAM - 4 GB | OPPO A57s has more RAM than Realme C21. |
|---|---|---|---|
| Internal Memory Size (Storage Capacity) | 32 GB | 128 GB | OPPO A57s has more internal memory than Realme C21. |
| Memory Interface | - | eMMC 5.1 | |
| Supported Flash Memory Cards (Expandable Memory) | microSD | microSDHC, microSD, microSDXC - up to 1 TB |
| CAMERA | Realme C21 | OPPO A57s |
|---|
| MAIN CAMERA |
|---|
| Number of Main Cameras | 3 | 2 | |
|---|---|---|---|
| Sensor Resolution | 13 Megapixel | 50 Megapixel | OPPO A57s has better camera resolution than Realme C21. |
| Sensor Size | - | 1/2.76" | |
| Sensor Name | - | Samsung S5KJN1 | |
| Lens Aperture | F/2.2 | F/1.8 | OPPO A57s has better lens aperture than Realme C21. |
| Lens Construction | 5-element | 5-element | |
| Field of View (FoV) | - | 77 degree(s) | |
| Pixel Size | - | 0.64 μm | |
| Focus Adjustment | Automatic | Automatic | |
| Minimum Focal Length (Focal Distance) | - | 27 mm | |
| Digital Zoom | 4x | 5x | OPPO A57s has better digital zoom than Realme C21. |
| Special Effects | HDR | Stickers | |
| Camera Modes | Panorama, Time-lapse mode, Slow motion mode, Beauty mode, Expert Mode, Nightscape capture mode, Portrait, Filter mode, Super nightscape | Panorama, Time-lapse mode, Pro mode, Portrait, Night | |
| Light Source | LED flash | LED flash | |
| Video Resolutions | 1920 x 1080 (1080p) at 30 fps | 1920 x 1080 (1080p) at 30 fps, 1280 x 720 (720p) at 30 fps | |
| Camera Features (Functions) | Phase Detect Auto-Focus (PDAF), AI Triple camera, Chroma boost | - |
| SECOND CAMERA |
|---|
| Sensor Resolution (2nd Camera) | 2 Megapixel | 2 Megapixel | Both phones have the same second camera resolution. |
|---|---|---|---|
| Sensor Size (2nd Camera) | - | 1/5" | |
| Lens Aperture (2nd Camera) | F/2.4 | F/2.4 | Both phones have the same second camera lens aperture. |
| Lens Element Qty (2nd Camera) | 3-element | 3-element | |
| Field of View (2nd Camera) | - | 89 degree(s) | |
| Pixel Size (2nd Camera) | - | 1.75 μm | |
| Minimum Focal Length (2nd Camera) | - | 21 mm | |
| Camera Functions (2nd Camera) | B&W lens | Monochrome |
| THIRD CAMERA |
|---|
| Sensor Resolution (3rd Camera) | 2 Megapixel | - | |
|---|---|---|---|
| Lens Aperture (3rd Camera) | F/2.4 | - | |
| Lens Element Qty (3rd Camera) | 3-element | - | |
| Camera Functions (3rd Camera) | Macro camera | - | |
| Camera Features (3rd Camera) | 4cm macro photography | - |
| FRONT CAMERA |
|---|
| Number of Front Cameras | 1 | 1 | |
|---|---|---|---|
| Sensor Resolution (Front) | 5 Megapixel | 8 Megapixel | OPPO A57s has better front camera resolution than Realme C21. |
| Sensor Size (Front) | - | 1/1.4" | |
| Sensor Name (Front) | - | Omnivision OV08D10 sensor | |
| Lens Aperture (Front) | F/2.2 | F/2.0 | OPPO A57s has better front lens aperture than Realme C21. |
| Lens Element Qty (Front) | 3-element | 5-element | |
| Field of View (Front) | - | 79 degree(s) | |
| Pixel Size (Front) | - | 1.12 μm | |
| Focus Adjustment | - | Focus free | |
| Min Focal Length (Front) | - | 26 mm | |
| Special Effects (Front) | HDR | Stickers | |
| Camera Modes (Front) | Time-lapse mode, Beauty mode, portrait mode, AI Beauty, Filter mode, Panoramic mode | Panorama, Time-lapse mode, Portrait | |
| Face Recognition (Face ID) | Face recognition | - | Realme C21 has face detection. |
| Video Resolutions (Front) | - | 1920 x 1080 (1080p) at 30 fps, 1280 x 720 (720p) at 30 fps |
| BATTERY AND CHARGING | Realme C21 | OPPO A57s |
|---|
| Battery Capacity (Battery Size) | 5000 mAh | 5000 mAh | Both phones have the same battery capacity. |
|---|---|---|---|
| Fast Charging Technology | - | SuperVOOC Flash Charge technology | OPPO A57s has fast charging technology. |
| Standby Time | - | 304 hours | |
| Talk Time | - | 1800 minutes | |
| Run Time Details | - | Talk: up to 1800 min Standby (4G): up to 304 hrs Playback (video): up to 13.4 hrs Playback (audio (via speakers, 50% volume)): up to 40 hrs |
| CELLULAR | Realme C21 | OPPO A57s |
|---|
| Technology | WCDMA (UMTS) / GSM | WCDMA (UMTS) / GSM | |
|---|---|---|---|
| Mobile Broadband Generation | 4G | 4G | Both phones have the same mobile network generation. |
| Operating System | Android 10 | ColorOS 12.1 (based on Android 12) | |
| User Interface | Realme UI | - | |
| Navigation | GPS, A-GPS, GLONASS, BeiDou | GPS, A-GPS, GLONASS, BeiDou, Galileo, QZSS |
| COMMUNICATIONS | Realme C21 | OPPO A57s |
|---|
| Data Transmission | FDD-LTE, TDD-LTE | VoLTE, FDD-LTE, TDD-LTE, VoWiFi | |
|---|---|---|---|
| 2G Band | 850 GSM, 900 GSM, 1800 GSM, 1900 GSM | 850 GSM, 900 GSM, 1800 GSM, 1900 GSM | |
| 3G UMTS Band | Band 1, Band 5, Band 8 | Band 1, Band 5, Band 8 | |
| 3G UMTS Frequency | 2100, 850, 900 | 2100, 850, 900 | |
| 4G LTE Band | Band 1, Band 3, Band 5, Band 7, Band 8, Band 20, Band 28, Band 38, Band 40, Band 41 | Band 1, Band 3, Band 5, Band 7, Band 8, Band 20, Band 28, Band 38, Band 40, Band 41 | |
| 4G LTE Frequency | FDD 2100, FDD 1800+, FDD 850, FDD 2600, FDD 900, FDD 800 DD, FDD 700 APT, TDD 2600, TDD 2300, TDD 2500 | FDD 2100, FDD 1800+, FDD 850, FDD 2600, FDD 900, FDD 800 DD, FDD 700 APT, TDD 2600, TDD 2300, TDD 2500 | |
| Wireless Interface | IEEE 802.11b/g/n | IEEE 802.11a/b/g/n/ac | |
| Bluetooth | Bluetooth 5.0 | Bluetooth 5.3 BLE | |
| NFC | - | Yes | OPPO A57s has NFC reader for mobile payments. |
| MEDIA | Realme C21 | OPPO A57s |
|---|
| Supported Digital Audio Standards | - | WAV, WMA, AAC, AMR, MP3, FLAC, AC-3, OGG, MIDI, APE (Monkey's Audio), LDAC, OPUS, MID, SBC, apt-X HD | |
|---|---|---|---|
| Supported Digital Video Standards | - | MKV, FLV, AVI, MOV, ASF, 3GP, M4V, TS, M2TS, WebM, MP4 | |
| Sound Enhancements | - | Dirac sound technologies |
| FEATURES | Realme C21 | OPPO A57s |
|---|
| Phone Functions | Speakerphone, voice control, call timer, conference call, flight mode, voice dialing, vibrating alert | - | |
|---|---|---|---|
| Sensors | Accelerometer, proximity sensor, magnetometer, light sensor | Accelerometer, proximity sensor, magnetometer, gravity sensor, brightness sensor | |
| Security Devices | Fingerprint reader | Face recognition, fingerprint reader (side) | |
| Additional Phone Features | Super power saving mode, HyperEngine technology, Reverse charging | Noise reduction microphone, Fast Charging, 3 years of Security Updates, 2 years of OS upgrades, Cooling Graphite Thermal Pad, Reverse charging, super-linear dual speakers |
| OTHERS | Realme C21 | OPPO A57s |
|---|
| Included Accessories | USB cable, power adapter, SIM card removal tool | SIM card removal tool, USB-C charging cable, protective film, SuperVOOC 33W power adapter | |
|---|---|---|---|
| Compliant Standards | TUV Rheinland | IPX4 |
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